Oct. 9: Mount Everest is 3.7 metres shorter than what has been believed since its altitude was measured 30 years ago, the Chinese government announced today.

The elevation of Mount Everest’s summit rock is 8,844.43 metres, not 8,848.13 metres as measured in 1975, Chen Bangzu, the director-general of the Chinese State Bureau of Surveying and Mapping, said in Beijing.

He acknowledged that international bodies and other countries might take time to accept the new measurement.

Scientists in India familiar with the geology of the Himalayas said that it was too early to comment on the Chinese claim. “We need to see the data,” a senior scientist said.

Chinese researchers had climbed the Everest ? Mount Qomolangma as the Chinese call it ? in May this year to measure the height of the world’s tallest peak with the help of sophisticated instruments that use satellites and radars to study distances.

“The elevation data of Mount Qomolangma published in 1975 will cease to be used in China,” the official said while presenting the results of the survey carried out by the surveyors.

The Chinese used satellite-based global positioning system (GPS) devices to arrive at the new figure. “But GPS picks up horizontal movements much better than vertical movements,” said Dr Harsh Gupta, a former director of the National Geophysical Research Institute in Hyderabad.

Chen told reporters in Beijing that the updated figure did not mean that the mountain had shrunk over time.

“This data is so far the most detailed and precise among all previous domestic and international surveys,” the official was quoted by China Central Television as saying.

However, Chen said: “We cannot arrive at the conclusion that Everest has become shorter because there have been problems of surveying technology in previous measurements.”

An earlier Chinese expedition in 1975 had used traditional trigonometric techniques to measure the height the peak, Xinhua news agency had said earlier this year. An American team in 1999 had calculated the height of Mount Everest to be 8,850 metres.

The Chinese expedition in May this year used radar to measure the thickness of ice and snow that cover the summit rock. Chen said the ice blanket on the summit is 3.5 metres. This is higher than 0.9 metres estimated by surveyors in 1975 by just thrusting a steel rod into the ice.

There have been concerns in recent years on the impact of global warming on the Himalayas. Last year, Xinhua had quoted Chinese scientists as saying that Mount Everest had lost 1.3 metres of ice cover between 1966 and 1999.

Indian scientists who have been studying the glacial melting in the Himalayas said loss of snow over Mount Everest would not be surprising. “The impact on its height would depend on whether net loss is greater than what it receives each year,” said Anil Kulkarni, a glacier scientist at the Space Applications Centre, Ahmedabad.